DNA Drug Sensitivity Testing™ for
Cancer Medications

Genelex will be happy to mail information to you or to your healthcare provider on your behalf, simply complete the request form.

Are you taking or considering medication to treat or prevent cancer?

Are you taking additional medications?

Personalized medication management including DNA testing is extremely important for the proper treatment of cancer because finding the right drug and dose is so vitally important. This is not surprising to people that study genetics - research shows that of all the clinical factors such as age, sex, weight, general health and liver function that alter a patient's response to drugs, genetic factors account for a significant proportion.

Over half of all medications including the majority of cancer medications are metabolized by three enzymes in the liver: CYP2D6, CYP2C9, and CYP2C19. NAT2 and 1A2 are also involved in metabolism of many cancer medications. Your genes are the main factor determining the level of these enzymes in your liver - if you have too much of the enzyme, you process the medication too quickly, too little of the enzyme and the medication builds up in your bloodstream potentially causing adverse reactions or side effects. Without knowing your genetics, your physician may need to go through months of trial-and-error prescribing to find the right drug and dose for you.

Population Frequency of Cytochrome P450 (CYP) Metabolizer Types

In addition to cancer medications metabolized by the pathways above, there are specialized test for the following cancer medications:

Nolvadex® (tamoxifen)

Camptosar (irinotecan)

Fluorouracil (5-FU)

Other cancer medications and involved metabolic pathway:

Now your healthcare provider can help optimize your response to cancer drugs and many other medications by ordering DNA testing. Your results will be entered into our personalized medication management software, GeneMedRx You or your healthcare providers can log in to see if current or future medications are predicted to cause drug-drug or drug-gene interactions so dosage and selection can be catered to your needs. You receive a 90-day subscription free with your testing; additional one year extensions are available for a nominal fee. Of course, your DNA never changes so the testing only needs to be done once in a lifetime.

Click here to view a list of drugs for which DNA testing may be helpful.

The Testing Process

The process is simple. You can order testing directly if you have a physician prescription or your healthcare provider can request testing for you. We send a cheek swab collection kit with directions by mail. Samples are submitted using the enclosed return mailer and results are provided in ten days or less. Faster testing is available for an additional charge. Call a DNA testing consultant at (800) 523-3080 for details and to order, or request information to you or to your healthcare provider on your behalf, simply complete the request form.

References

http://www.medscape.com/viewarticle/508543_2

Oesterheld, Jessica, M.D. GeneMedRx Drug Metabolism Tables

Aynacioglu AS, et al. Frequency of cytochrome P450 CYP2C9 variants in a Turkish population and functional relevance for phenytoin. Br J Clin Pharmacol 1999; 48(3):409-415

Scordo MG, et al. Genetic polymorphism of cytochrome P450 2C9 in a Caucasian and a black African population. Br J Clin Pharmacol 2001; 52(4):447-450.

Goldstein JA, Ishizaki T, Chiba K, de Morais SM, Bell D, Krahn PM, Evans DA. Frequencies of the defective CYP2C19 alleles responsible for the mephenytoin poor metabolizer phenotype in various Oriental, Caucasian, Saudi Arabian and American black populations. Pharmacogenetics 1997, 7: 59-64

Blaisdell J, et al. Identification and functional characterization of new potentially defective alleles of human CYP2C19. Pharmacogenetics. 2002 Dec;12(9):703-11

Ibeanu GC,  et al. Identification of new human CYP2C19 alleles (CYP2C19*6 and CYP2C19*2B) in a Caucasian poor metabolizer of mephenytoin. J Pharmacol Exp Ther. 1998 Sep;286(3):1490-5.

Ibeanu GC, et al. An additional defective allele, CYP2C19*5, contributes to the S-mephenytoin poor metabolizer phenotype in Caucasians. Pharmacogenetics. 1998 Apr;8(2):129-35.

De Morais SM, Wilkinson GR, Blaisdell J, Nakamura K, Meyer UA, Goldstein JA, The major genetic defect responsible for the polymorphism of S-mephenytoin metabolism in humans. J Biol Chem. 1994 Jun 3;269(22):15419-22

Ferguson RJ, De Morais SM, Benhamou S, Bouchardy C, Blaisdell J, Ibeanu G, Wilkinson GR, Sarich TC, Wright JM, Dayer P, Goldstein JA. A new genetic defect in human CYP2C19: mutation of the initiation codon is responsible for poor metabolism of S-mephenytoin. J Pharmacol Exp Ther. 1998 Jan;284(1):356-61.

Xiao ZS, Goldstein JA, Xie HG, Blaisdell J, Wang W, Jiang CH, Yan FX, He N, Huang SL, Xu ZH, Zhou HH. Differences in the incidence of the CYP2C19 polymorphism affecting the S-mephenytoin phenotype in Chinese Han and Bai populations and identification of a new rare CYP2C19 mutant allele. J Pharmacol Exp Ther. 1997 Apr;281(1):604-9.

Cozza KL, Armstrong SC, Oesterheld JR (2003) Drug Interaction principles for Medical Practice. American Psychiatric Publishing Inc

Werner Schroth; Matthew P. Goetz; Ute Hamann; et al. Association Between CYP2D6 Polymorphisms and Outcomes Among Women With Early Stage Breast Cancer Treated With tamoxifen JAMA. 2009;302(13):1429-1436

Goetz MP et al. The impact of Cytochrome P450 2D6 metabolism in women receiving adjuvant tamoxifen. Breast Cancer Res Treat 2007; 101 (1): 113-21

Borges S et al. Quantitative effect of CYP2D6 genotype and inhibitors on tamoxifen metabolism: implication for optimization of breast cancer treatment. Clin Pharmacol Ther 2006;80(1):61-74

Note: Testing requires a prescription from a physician and is not currently available in New York state.